Frame structure for vehicle and vehicle

ABSTRACT

A frame structure for a vehicle includes a vehicle body frame, a pair of occupant seats, and a center pipe. The vehicle body frame has a front-rear direction. The pair of occupant seats includes a driver&#39;s seat and a passenger seat and are arranged side by side in a vehicle width direction substantially orthogonal to the front-rear direction. The center pipe extends in the front-rear direction and is arranged substantially on a center line of a vehicle body so as to pass through positions between the driver&#39;s seat and the passenger seat in the vehicle body frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to JapanesePatent Application No. 2008-253176, filed Sep. 30, 2008. The contents ofthis application are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a frame structure for a vehicle and avehicle.

2. Discussion of the Background

There is a conventionally-known vehicle body frame structure for avehicle, which is intended to reduce the weight of a vehicle and toreduce the manufacturing costs (refer to, for example, Japanese PatentApplication Publication No. 2006-103370). The vehicle body framestructure described in Japanese Patent Application Publication No.2006-103370 has a vehicle body frame including: a front frame portionwhich supports a front-wheel drive system; a center frame portion whichforms a space for occupants; and a rear frame portion which supports arear-wheel drive system. In the center frame portion, the structure ofan underfloor frame is formed to be a two-layer structure having anupper portion and a lower portion. The upper portion includes lowerframes and side square-U-shaped frames, and the lower portion includessubframes and upper side frames.

In the vehicle body frame structure described in Japanese PatentApplication Publication No. 2006-103370, the structure of the underfloorframe in the center frame portion is formed to be the two-layerstructure having the upper and lower portions. This structuresufficiently secures the rigidity of the underfloor frame, but increasesthe height of the floor, thus leading to an increase in the height ofthe seats for the occupants. On the other hand, in order to enhance thetraveling performance required for vehicles such as MUVs (multi utilityvehicle), it is desirable that the vehicles have a low floor and a lowcenter of gravity in addition to an improvement in rigidity of thevehicle body frame.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a frame structure fora vehicle includes a vehicle body frame, a pair of occupant seats, and acenter pipe. The vehicle body frame has a front-rear direction. The pairof occupant seats include a driver's seat and a passenger seat and arearranged side by side in a vehicle width direction substantiallyorthogonal to the front-rear direction. The center pipe extends in thefront-rear direction and is arranged substantially on a center line of avehicle body so as to pass through positions between the driver's seatand the passenger seat in the vehicle body frame.

According to another aspect of the present invention, a vehicle includesan internal combustion engine, a vehicle body frame, a pair of occupantseats, and a center pipe. The vehicle body frame has a front-reardirection and supports the internal combustion engine. The pair ofoccupant seats include a driver's seat and a passenger seat and arearranged side by side in a vehicle width direction substantiallyorthogonal to the front-rear direction. The center pipe extends in thefront-rear direction and is arranged substantially on a center line of avehicle body so as to pass through positions between the driver's seatand the passenger seat in the vehicle body frame.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a left-side view of a vehicle employing a frame structure fora vehicle according to an embodiment of the present invention;

FIG. 2 is a plan view of the vehicle illustrated in FIG. 1;

FIG. 3 is a plan view of chief parts of a power transmission mechanismof the vehicle illustrated in FIG. 1;

FIG. 4 is a right-side view of the vehicle illustrated in FIG. 1;

FIG. 5 is a perspective view illustrating the frame structure of thevehicle illustrated in FIG. 1;

FIG. 6 is a plan view illustrating, in an enlarged manner, chief partswhere wires are arranged;

FIG. 7 is a side view taken along the line VII-VII in FIG. 2, andillustrating, in an enlarged manner, an inside of a center consolecover;

FIG. 8 is a plan view illustrating, in an enlarged manner, rear chiefparts illustrated in FIG. 2;

FIG. 9 is a rear view of the vehicle illustrated in FIG. 1;

FIG. 10 is a rear view illustrating, in an enlarged manner, chief partsof an intake structure illustrated in FIG. 9; and

FIG. 11 is a side view illustrating, in an enlarged manner, a rear frameportion illustrated in FIG. 1.

DESCRIPTION OF THE EMBODIMENTS

The embodiments will now be described with reference to the accompanyingdrawings, wherein like reference numerals designate corresponding oridentical elements throughout the various drawings.

Hereinafter, a frame structure for a vehicle according to an embodimentof the present invention will be described by giving an MUV (multiutility vehicle) as an example. Note that the drawings should be viewedin the direction of orientation of reference numerals.

As illustrated in FIGS. 1 to 3, a vehicle 1 according to the embodimentincludes a vehicle body frame 30 which includes a front frame portion 2,a center frame portion 3, and a rear frame portion 4 so as to constitutea vehicle body B. A front-wheel suspension system (not illustrated)which suspends left and right front wheels 5 is attached to the frontframe portion 2. In addition, a front-wheel drive system including afront differential gear unit 81, front drive shafts 82, and the like;steering members (including a steering shaft 6 and a steering wheel 7attached to an upper end of the steering shaft 6) for steering the frontwheels 5; and the like are supported on the front frame portion 2.

A pair of occupant seats 11, constituting a driver's seat 9 and apassenger seat 10 arranged side by side in a vehicle width direction,are attached to the center frame portion 3, so that a space foroccupants is formed. A fuel tank 12 is disposed in a space below thepassenger seat 10. A front propeller shaft 83 coupling a power unit Pand a front differential gear unit 81 is disposed between the driver'sseat 9 and the passenger seat 10.

A rear-wheel suspension system (not illustrated) which suspends left andright rear wheels 15 is attached to the rear frame portion 4. Inaddition, a rear-wheel drive system including, for example, a rearpropeller shaft 86, a rear differential gear unit 84, rear drive shafts85; and the like are supported on the rear frame portion 4 in additionto the power unit P including an internal combustion engine 13 and atransmission 14.

As illustrated in FIG. 3, the power unit P supported on the rear frameportion 4 is laid out vertically in such a manner that a crankshaft 16of the internal combustion engine 13 is directed in a front-reardirection of the vehicle body. An output shaft 80 to which a drivingforce is transmitted from the crankshaft 16 is disposed substantially ona center line CL of the vehicle body. The output shaft 80 is coupled ata front end thereof to the front propeller shaft 83 and is coupled at arear end thereof to the rear propeller shaft 86.

The rear propeller shaft 86 is connected to the rear differential gearunit 84 disposed substantially on the center line CL of the vehiclebody. The driving force of the internal combustion engine 13 istransmitted to the left and right rear wheels 15 via the rear propellershaft 86, the rear differential gear unit 84, and then the rear driveshafts 85 connected to the rear differential gear unit 84.

The front propeller shaft 83 is provided with a reduction gear 90 at anintermediate portion of the front propeller shaft 83. The frontpropeller shaft 83 is constituted of a first propeller shaft 87 and asecond propeller shaft 88. The first propeller shaft 87 is disposed atthe rear of the reduction gear 90, while the second propeller shaft 88is disposed at the front of the reduction gear 90. The reduction gear 90transmits the rotational force of the first propeller shaft 87 to thesecond propeller shaft 88 while converting the rotational direction ofthe first propeller shaft 87 into the reverse direction in order torotate the front wheels 5 and the rear wheels 15 in the same direction.Accordingly, the driving force of the internal combustion engine 13 istransmitted to the left and right front wheels 5 via the first propellershaft 87, the reduction gear 90, the second propeller shaft 88, thefront differential gear unit 81, and then the front drive shafts 82connected to the front differential gear unit 81.

As illustrated in an enlarged manner in FIG. 8, a throttle valve unit 19is connected to a rear portion of a cylinder head 18 of the internalcombustion engine 13 via an intake manifold 20. An exhaust pipe 120,which will be described later, is connected to a front portion of thecylinder head 18. An air cleaner 110 including first and second aircleaner chambers 111 and 112, which will be described later, isconnected to a rear portion of the throttle valve unit 19 via aconnecting tube 117. Moreover, a fuel supply pipe 21 and a wire harness23 are connected to the throttle valve unit 19. The fuel supply pipe 21extends from the fuel tank 12. The wire harness 23 is arranged to extendfrom a battery case 22 including the battery case 22, an ECU 26, and thelike.

Moreover, as illustrated in FIGS. 2 and 4, a radiator 24 disposed in thefront frame portion 2 is connected to the internal combustion engine 13via two water supply pipes 25. Thus, cooling water for cooling theinternal combustion engine 13 circulates between the radiator 24 and theinternal combustion engine 13 through the water supply pipes 25.

Note that, in FIG. 1, reference numeral 26 denotes a front cover;reference numeral 27 denotes an instrument panel; reference numeral 28denotes a center console cover including a center cover member 28 a aswell as a pair of left and right cover members 28 b.

As illustrated in FIGS. 4 and 5, the vehicle body frame 30 includes apair of lower frames 34 disposed respectively in left and right lowerportions of the vehicle body B and extending in the front-reardirection. Each of the lower frames 34 forms a front lower frame 31, acenter lower frame 32, and a rear lower frame 33.

In the front frame portion 2, a pair of left and right front upperframes 70 extend upward from front ends of the respective front lowerframes 31, further extend rearward, and then are joined to a front uppercross-member 44. In this manner, the left and right front upper frames70 cover a front portion of the vehicle body B from above. The frontlower frames 31 and the front upper frames 70 are coupled to one anotherby a square U-shaped frame 71.

In addition, rising portions of the square U-shaped frame 71 are coupledrespectively to rising portions of the front upper frames 70 byfront-suspension support pipes 72 each formed into a substantiallyL-shape. Two brackets 63 are fixed onto each of the front lower frames31 and the front-suspension support pipes 72, and the front-wheelsuspension system is swingably disposed on the brackets 63. Thefront-wheel suspension system rotatably suspends the left and rightfront wheels 5.

On the other hand, in the rear frame portion 4, a pair of left and rightrear upper frames 75 extend upward from rear ends of the rear lowerframes 33, thereafter are bent to extend frontward in such a manner asto cover the power unit P including the internal combustion engine 13,and then are joined respectively to a pair of center upright frames 40.The center upright frames 40 extend upward from portions, behind theoccupant seats 11, of the respective center lower frames 32. Horizontalportions of the rear upper frames 75 are vertically connected to therear lower frames 33 respectively by rear upright frames 76, each ofwhich is inclined frontward while extending downward. Moreover, the rearupright frames 76 are connected respectively to perpendicular portionsof the corresponding rear upper frames 75 respectively byrear-suspension support pipes 77.

Two brackets 78 are fixed respectively onto front and rear portions ofeach of the rear lower frames 33 and the rear-suspension support pipes77. The rear-wheel suspension system is swingably disposed on the fourbrackets 78 in total. The rear-wheel suspension system suspends the leftand right rear wheels 15 in a manner that the rear wheels 15 arerotatable.

In the center frame portion 3, a pair of left and right side frames 51,which extend in the front-rear direction, are disposed respectivelyoutside the center lower frames 32 in the vehicle width direction. Theside frames 51 are joined to the respective lower frames 34 byconnecting pipes 66 and connecting pipes 67. The connecting pipes 66 areconnected to front portions of the respective center lower frames 32,while the connecting pipes 67 are connected to intermediate portions ofthe respective center upright frames 40.

Each of the side frames 51 includes a front rising portion 51 a, a rearrising portion 51 b, and a horizontal portion 51 c joining the front andrear rising portions 51 a and 51 b, and is thus formed in asubstantially square U-shape, which is convex downward.

In each of the substantially square U-shaped side frames 51, the frontrising portion 51 a and the rear rising portion 51 b are coupled to eachother by a side pipe 52 in the front-rear direction. End portions of therespective front rising portions 51 a of the pair of side frames 51 arecoupled to each other by the front upper cross-member 44 in the vehiclewidth direction. Middle portions of each rear rising portion 51 b andthe corresponding horizontal portion 51 c are coupled to each other by aseat supporting pipe 53 having a substantially L shape.

A pair of side upper frames 55, each formed into a substantially squareU shape, are each connected to the front rising portion 51 a and therear rising portion 51 b of a corresponding one of the pair of sideframes 51 in such a manner that the side upper frame 55 is convexupward. The pair of side upper frames 55 are coupled to each other inthe vehicle width direction by: a first upper cross-member 54, to whichthe pair of center upright frames 40 are joined at upper end portionsthereof; two roof cross-members 56 and 57; and a cross-member 58 forheadrest, which is joined at a middle portion thereof to the first uppercross-member 54.

A first seat cross-member 61 is laid between the pair of seat supportingpipes 53 with brackets therebetween. In addition, a pair of second seatcross-members 62 are joined to the rear rising portions 51 b of therespective side frames 51 with brackets therebetween. The second seatcross-members 62 are joined to a rear cross-member 64 which connects thepair of center upright frames 40 to each other at portions lower thanthe middle portions thereof. The first and second seat cross-members 61and 62 as well as coupling frames 65, which couple the respective secondseat cross-members 62 to the first seat cross-member 61 in thefront-rear direction, constitute seat frames. Seat pipes 60 (refer toFIG. 9) for the driver's seat 9 and the passenger seat 10 are attachedto the seat frames.

In addition, in the center frame portion 3, a center pipe 35 isprovided. The center pipe 35 passes between the driver's seat 9 and thepassenger seat 10 and is arranged above the lower frames 34 to extend inthe front-rear direction substantially on the center line CL of thevehicle body. Accordingly, the center frame portion 3 has a structure inwhich the center pipe 35 and the pair of lower frames 34 are disposedrespectively on the upper and lower sides in the center portion in thevehicle width direction, and the side pipe 52 and the side frame 51 aredisposed on the upper and lower sides in each of the side portions. Thisstructure makes it possible to improve the rigidity of the center frameportion 3 as well as to achieve a low floor and a low center of gravity.

As illustrated in an enlarged manner also in FIG. 7, the center pipe 35includes an upper center pipe 36, a down center pipe 37, an uprightcenter pipe 38, and a front center pipe 39. These members 36, 37, 38,and 39 are joined together at a joint point J located in front of theoccupant seats 11.

The upper center pipe 36 extends frontward while being joined at one endthereof to a center portion of a rear upper cross-member 41 whichcouples the pair of center upright frames 40 to each other. The downcenter pipe 37 extends upward and frontward while being joined at oneend thereof to a center portion of a rear lower cross-member 42 which islaid between the center lower frames 32 at a position below the occupantseats 11.

The upright center pipe 38 extends rearward and upward while beingjoined at one end thereof to a center portion of a front lowercross-member 43 which is laid between the center lower frames 32 at aposition in front of the occupant seats 11. The front center pipe 39 isa pipe member that is formed into a substantially V shape with twobranches extending frontward respectively to the left and right from thejoint point J as the base point. An end portion of each of the left andright branches is joined to the front upper cross-member 44 in avicinity of the joint portion of a corresponding one of the front upperframes 70 to the front upper cross-member 44.

Note that, in the embodiment, the pair of center upright frames 40 andthe rear upper cross-member 41 are frames, which constitute, behind theoccupant seats, the vehicle body frame; the center lower frames 32 andthe rear lower cross-member 42 are frames constituting a lower frame;and the front upper frames 70 and the front upper cross-member 44 areframes constituting, in front of the occupant seats, the vehicle bodyframe.

On the center pipe 35 constituted as described above, a shift lever 105is attached to a portion above a vicinity of the joint point J havingincreased rigidity, and a side-brake lever 106 is attached to a portionabove an intermediate portion of the upper center pipe 36. Note that,the steering shaft 6, which is a steering member, is attached to thefront upper cross-member 44 with a subframe 107 interposed therebetween.Wires extend from the shift lever 105, the side-brake lever 106, and thesteering shaft 6, as well as from foot controls 91, such as a brakepedal and an acceleration pedal, disposed on the driver's seat 9 side,and the like. These extending wires are gathered in an electricconnection box 103, and then bundled into a single wire harness 104,which is eventually connected to the battery case 22 provided behind thedriver's seat 9.

In addition, as illustrated in FIGS. 2, 3 and 7, the first propellershaft 87 is located below and along the center pipe 35 substantially onthe center line CL of the vehicle body. The first propeller shaft 87 isdisposed also in such a manner as to overlap the fuel tank 12 in a sideview, in other words, in such a manner that the first propeller shaft 87and the fuel tank 12 are arranged side by side in the vehicle widthdirection. The second propeller shaft 88 connected to the reduction gear90 is disposed offset toward the passenger seat 10 in the vehicle widthdirection with respect to the first propeller shaft 87. Moreover, thesecond propeller shaft 88 is coupled, on the passenger seat 10 side, tothe front differential gear unit 81 disposed substantially on the centerline CL of the vehicle body above the front lower frames 31.

As described above, since the front propeller shaft 83 is arrangedsubstantially along the center pipe 35, the torsion in the vehicle 1 isunlikely to act on the front propeller shaft 83. In addition, since thesecond propeller shaft 88 is disposed offset toward the passenger seat10 in the vehicle width direction, a large space for occupants can besecured even with the lowered floor, and also, the flexibility in layoutof the foot controls 91 is improved, so that the foot controls 91 can bedisposed at positions where the foot controls 91 are easily operated.

Moreover, the reduction gear 90 is located in front of the pair ofoccupant seats 11, and also behind the foot controls 91, such as thebrake pedal and acceleration pedal, disposed on the driver's seat 9side, and is disposed between the down center pipe 37 and the uprightcenter pipe 38.

The two water supply pipes 25, which connect the radiator 24 and theinternal combustion engine 13, as well as the wire harness 104, whichelectrically connects the electric connection box 103 and the batterycase 22, are also disposed offset toward the passenger seat 10 side inthe vehicle width direction, partially in a region in front of theupright center pipe 38, as in the case of the front propeller shaft 83.

Accordingly, the center console cover 28 provided between the driver'sseat 9 and the passenger seat 10 houses the center pipe 35, the frontpropeller shaft 83, the reduction gear 90, the water supply pipes 25,the wire harness 104, the shift lever 105, and the side brake lever 106,while a front portion of the center console cover 28 is offset towardthe passenger seat 10 side.

With this arrangement, the water supply pipes 25 and the wire harness104 are compactly arranged by utilizing the dead space. As a result, alarge space for occupants can be secured, and also, the flexibility inlayout of the foot controls 91 is improved, so that the foot controls 91can be disposed at positions where the foot controls 91 are easilyoperated.

Further, while the vehicle body frame 30 is formed in a bilaterallysymmetrical arrangement, the front differential gear unit 81, thereduction gear 90, the internal combustion engine 13, the reardifferential gear unit 84, and the like, which are major heavycomponents, are disposed substantially on the center line CL of thevehicle body. As a result, a favorable weight balance between the leftand right sides is achieved to increase the stability of the vehicle 1.

As illustrated in FIGS. 8 to 10, the air cleaner 110, which is anair-intake device, is disposed behind the passenger seat 10 on the rightside of the internal combustion engine 13, and includes the first aircleaner chamber 111 and the second air cleaner chamber 112.

A snorkel 113 is connected to the first air cleaner chamber 111 via aduct attached to an outer side surface of the first air cleaner chamber111 in the vehicle width direction. The snorkel 113 is disposed behindthe passenger seat 10 and has a cover 114 for covering its opening. Thefirst air cleaner chamber 111 and the second air cleaner chamber 112face each other in the vehicle width direction with the rear uprightframe 76 on the corresponding side being partially sandwichedtherebetween, and communicate with each other via a coupling tube 116.In addition, the second air cleaner chamber 112 is connected to theinternal combustion engine 13 via the connecting tube 117.

Accordingly, the first air cleaner chamber 111 is disposed outside thecorresponding rear upright frame 76 in the vehicle width direction, andthe second air cleaner chamber 112 is disposed inside the rear uprightframe 76 in the vehicle width direction. In addition, an air cleanerelement 115 for removing dust in the air is housed in the first aircleaner chamber 111.

In the air cleaner 110 as described above, external air is introducedfrom the snorkel 113; then dust in the air thus introduced is removed bythe air cleaner element 115 in the first air cleaner chamber 111; thepurified air is guided to the second air cleaner chamber 112 through thecoupling tube 116, and thereafter, is supplied to the internalcombustion engine 13 from the connecting tube 117.

Since the air cleaner 110 is constituted of: the first air cleanerchamber 111 disposed outward of the corresponding lower frame 34 in thevehicle width direction and the second air cleaner chamber 112 disposedinward thereof in the vehicle width direction. Accordingly, the aircleaner 110 having a large capacity can be compactly disposed in anarrow space surrounded by the frames. In addition, since the first aircleaner chamber 111 is disposed outward of the corresponding rearupright frame 76 in the vehicle width direction, a large space formaintenance of the air cleaner 110 can be secured. For this reason, amaintenance operation can be easily performed on the air cleaner 110,that is, the air cleaner 110 has an excellent maintainability.

It should be noted that the above-described effect can be obtained evenwhen the first and second cleaner chambers 111 and 112 are disposed tosandwich a part of the corresponding lower frame 34 or of thecorresponding rear upper frame 75 instead of the rear upright frame 76,in accordance with the position where these chambers 111 and 112 areattached.

Moreover, as illustrated in FIGS. 8 and 11, the exhaust pipe 120connected to the front portion of the cylinder head 18 first extendsfrontward, thereafter turns around and extends rearward, is further bentat substantially 90°, and linearly extends to the outside of the vehiclebody while being inclined downward with respect to the horizontal plane.Moreover, after reaching a region behind the driver's seat 9 in thevehicle width direction, the exhaust pipe 120 is bent to the inside ofthe vehicle body and linearly extends back substantially onto the centerline CL of the vehicle body while being inclined upward, and is thenconnected to a muffler 122 disposed to extend in the front-reardirection substantially on the center line CL of the vehicle body in therear frame portion 4. With this arrangement, an outermost extendingportion 121 of the exhaust pipe 120 extends to a region inside arearward extension line of the corresponding side frame 51 in thevehicle width direction and outside the corresponding rear upper frame75 in the vehicle width direction.

Accordingly, a required length can be secured for the exhaust pipe 120even in, for example, the vehicle 1 having the lowered floor, in whichthe space in the rear frame portion 4 is limited with the internalcombustion engine 13 disposed behind the occupant seats 11. Moreover,having many straight portions, the exhaust pipe 120 can be easilyprocessed, so that the number of assembly processes can be reduced andthat the manufacturing costs thus can be suppressed.

The outermost extending portion 121 of the exhaust pipe 120 extends tothe region inside the rearward extension line of the corresponding sideframe 51 in the vehicle width direction and outside the correspondingrear upper frame 75 in the vehicle width direction. With thisarrangement, the exhaust pipe 120 is protected while the length of theexhaust pipe 120 is sufficiently secured.

In addition, the exhaust pipe 120 extends back substantially onto thecenter line CL of the vehicle body within a region in front of the rearupright frames 76. This makes it possible to securely prevent aninterference of the exhaust pipe 120 with the rear-wheel suspensionsystem disposed rearward of the rear upright frames 76.

As described above, according to the frame structure for a vehicle ofthe embodiment, the center pipe 35 extends between the driver's seat 9and the passenger seat 10, and is arranged in the front-rear directionsubstantially on the center line CL of the vehicle body in the vehiclebody frame 30. This arrangement makes it possible to improve therigidity of the vehicle body frame 30.

In addition, the frame structure for a vehicle includes the pair of leftand right side frames 51 extending in the front-rear directionrespectively outside the lower frames 34 in the vehicle width direction.The front and rear portions of each side frame 51 are connected to eachother by the side pipe 52, and the center pipe 35 is arranged above thelower frames 34 to extend in the front-rear direction substantially onthe center line CL of the vehicle body. Accordingly, the rigidity of theside portions of the vehicle body frame 30 is secured by the pair ofside frames 51 and the pair of side pipes 52 disposed respectively onthe upper and lower sides, while the rigidity of the center portion ofthe vehicle body frame 30 is secured by the center pipe 35 and the pairof lower frames 34 disposed respectively on the upper and lower sides.With this structure, the height of the occupant seats and the floorheight can be lowered while the rigidity of the vehicle body frame 30 issufficiently maintained, so that a low floor and a low center of gravitycan be achieved.

Furthermore, the center pipe 35 includes the upper center pipe 36, thedown center pipe 37, the upright center pipe 38, and the front centerpipe 39. These members 36, 37, 38, and 39 are joined together at thejoint point J located in front of the occupant seats 11. Accordingly,this center pipe structure makes it possible to improve the rigidity ofthe vehicle body.

In addition, the frame structure for a vehicle includes the pair of leftand right front upper frames 70 extending from front ends of therespective front lower frames 31 so as to cover the front portion of thevehicle body B from above. Moreover, the front center pipe 39 formedinto the left and right branches is joined to the front uppercross-member 44 in the vicinities of the respective joint portions ofthe front upper frames 70 to the front upper cross-member 44. This makesit possible to further improve the rigidity of the vehicle body B, andalso to reduce a bending force acting on the front upper cross-member44.

In addition, since the front propeller shaft 83 which transmits thedriving force of the internal combustion engine 13 to the front-wheeldrive system is arranged substantially along the center pipe 35, thetorsion in the vehicle body B is unlikely to act on the front propellershaft 83. Moreover, the front propeller shaft 83 can be disposed byutilizing the dead space below the center pipe 35, which enables acompact layout, so that a large space for occupants can be secured.

Furthermore, the reduction gear 90, which converts the rotationaldirection of the front propeller shaft 83 into the reverse direction, islocated in front of the occupant seats 11, and also behind the footcontrols 91, and is disposed between the down center pipe 37 and theupright center pipe 38. Accordingly, the reduction gear 90 can bedisposed in the dead space where the rigidity of the vehicle body ishigh. As a result, it is possible to protect the reduction gear 90, andto enable a compact layout, which secures a large space for occupants.

In addition, since the center pipe 35 is provided in the center frameportion 3 having the space for occupants therein, the rigidity of thecenter frame portion 3 can be improved.

In addition, the radiator 24 is arranged in the front frame portion 2,and the internal combustion engine 13 is arranged in the rear frameportion 4. In this arrangement, the water supply pipes 25 connecting theradiator 24 and the internal combustion engine 13 are arrangedsubstantially along the center pipe 35 in such a manner as to extend ina region on the passenger seat 10 side of the upright center pipe 38 infront of the upright center pipe 38. This arrangement allows the watersupply pipes 25 to be arranged in the dead space with a high rigidity ofthe vehicle body. As a result, it is possible to protect the watersupply pipes 25, and to enable a compact layout, which secures a largespace for occupants.

Moreover, since the shift lever 105 is disposed in a vicinity of thejoint point J of the members 36, 37, 38, and 39 constituting the centerpipe 35, the shift lever 105 can be provided at a position where therigidity of the vehicle body is high and where the driver can easilyoperate the shift lever 105, with no provision of any separate supportbracket dedicated to the shift lever 105.

Furthermore, since the side brake lever 106 is disposed on the uppercenter pipe 36, the side brake lever 106 can also be provided at aposition where the driver can easily operate the side brake lever 106,with no provision of any separate support bracket dedicated to the sidebrake lever 106.

Moreover, the center console cover 28 provided between the driver's seat9 and the passenger seat 10 houses the center pipe 35, the frontpropeller shaft 83, the reduction gear 90, the water supply pipes 25,the wire harness 104, the shift lever 105, and the side brake lever 106.Accordingly, the above members can be gathered in the center of thevehicle body, and also covered with the center console cover 28. As aresult, the external appearance is improved and also a large space foroccupants is secured.

A first embodiment of the present invention provides a frame structurefor a vehicle including: a vehicle body frame; a pair of occupant seatsbeing arranged side by side in a vehicle width direction in the vehiclebody frame, and constituting a driver's seat and a passenger seat; and acenter pipe passing between the driver's seat and the passenger seat andbeing arranged in a front-rear direction substantially on a center lineof a vehicle body in the vehicle body frame.

A second embodiment of the present invention provides the followingcharacteristics in addition to the configuration of the firstembodiment. Specifically, the frame structure for a vehicle furtherincludes: a lower frame being disposed to extend in the front-reardirection in both of left and right lower portions of the vehicle body;a pair of left and right side frames extending in the front-reardirection outside the lower frame in the vehicle width direction; and apair of side pipes each connecting two portions of a corresponding oneof the side frames in the front-rear direction. Moreover, in the framestructure for a vehicle, the center pipe is arranged above the lowerframe to extend in the front-rear direction substantially on the centerline of the vehicle body.

A third embodiment of the present invention provides the followingcharacteristics in addition to the configuration of the first or secondembodiment. Specifically, in the frame structure for a vehicle, thecenter pipe includes: an upper center pipe extending to the front of thevehicle body from a frame constituting, behind the occupant seats, thevehicle body frame; a down center pipe extending upward and frontwardfrom a part, below and between the occupant seats, of a frameconstituting the lower frame; an upright center pipe extending rearwardand upward from a portion, in front of the occupant seats, of the lowerframe; and a front center pipe extending rearward and downward from aframe constituting, in front of the occupant seats, the vehicle bodyframe. Moreover, the upper center pipe, the down center pipe, theupright center pipe, and the front center pipe are joined together at ajoint point in front of the occupant seats.

A fourth embodiment of the present invention provides the followingcharacteristic in addition to the configuration of any one of the firstto third embodiments. Specifically, the frame structure for a vehiclefurther includes a pair of left and right front upper frames extendingupward from front ends of the front lower frames, thereafter extendingrearward and then being connected to the front upper cross-member, so asto cover a front portion of the vehicle body from above. Moreover, inthe frame structure for a vehicle, the front center pipe is formed intothe two branches extending frontward respectively to the left and rightfrom the joint point so as to be connected to the front uppercross-member respectively in vicinities of left and right joint portionsof the front upper frames to the front upper cross-member.

A fifth embodiment of the present invention provides the followingcharacteristic in addition to the configuration of any one of the firstto fourth embodiments. Specifically, a propeller shaft for transmittinga driving force from an internal combustion engine to the front-wheeldrive system is disposed along the center pipe.

A sixth embodiment of the present invention provides the followingcharacteristic in addition to the configuration of the fifth embodiment.Specifically, the frame structure for a vehicle further includes: a footcontrol operable by an occupant's foot; and a reduction gear connectedto an intermediate portion of the propeller shaft, and converting arotational direction of the propeller shaft into a reverse direction.Moreover, in the frame structure for a vehicle, the reduction gear islocated in front of the occupant seats, and also behind the footcontrol, and is disposed between the down center pipe and the uprightcenter pipe.

A seventh embodiment of the present invention provides the followingcharacteristic in addition to the configuration of any one of the firstto sixth embodiments. Specifically, in the frame structure for avehicle, the vehicle body frame includes: a front frame portionsupporting the front-wheel drive system; a center frame portion having aspace for occupants therein; and a rear frame portion supporting arear-wheel drive system, and the center pipe is provided in the centerframe portion.

According to the first embodiment of the present invention, since thecenter pipe passes between the driver's seat and the passenger seat andis arranged in the front-rear direction substantially on the center lineof the vehicle body in the vehicle body frame, it is possible to improvethe rigidity of the vehicle body frame.

According to the second embodiment of the present invention, the framestructure for a vehicle includes the pair of left and right side framesextending in the front-rear direction outside the lower frame in thevehicle width direction. In addition, the front and rear portions ofeach of the side frames are coupled by the corresponding one of the sidepipes, while the center pipe is arranged above the lower frame to extendin the front-rear direction substantially on the center line of thevehicle body. Accordingly, the rigidity of the side portions of thevehicle body frame is secured by the pair of side frames and the pair ofside pipes disposed respectively on the upper and lower sides, while therigidity of the center portion of the vehicle body frame is secured bythe center pipe and the lower frames disposed on the upper and lowersides. With this structure, the height of the occupant seats and thefloor height can be lowered while the rigidity of the vehicle body frameis sufficiently maintained, so that a low floor and a low center ofgravity can be achieved.

According to the third embodiment of the present invention, the centerpipe includes the upper center pipe, the down center pipe, the uprightcenter pipe, and the front center pipe, and these pipe members arejoined together at the joint point in front of the occupant seats.Accordingly, this center pipe structure makes it possible to improve therigidity of the vehicle body.

According to the fourth embodiment of the present invention, the framestructure for a vehicle further includes the pair of left and rightfront upper frames extending from the front ends of the front lowerframes in such a manner as to cover a front portion of the vehicle bodyfrom above. The front center pipe formed into the left and rightbranches is connected to the front upper cross-member in the vicinitiesof the left and right joint portions of the front upper frames to thefront upper cross-member. This makes it possible to further improve therigidity of the vehicle body, and also to reduce a bending force actingon the front upper cross-member.

According to the fifth embodiment of the present invention, thepropeller shaft for transmitting the driving force of the internalcombustion engine to the front-wheel drive system is disposed along thecenter pipe. Accordingly, the torsion in the vehicle body is unlikely toact on the propeller shaft. Moreover, the propeller shaft can bedisposed by utilizing the dead space below the center pipe, whichenables a compact layout, so that a large space for occupants can besecured.

According to the sixth embodiment of the present invention, thereduction gear converting the rotational direction of the propellershaft into a reverse direction is located in front of the occupantseats, and also behind the foot control, and is disposed between thedown center pipe and the upright center pipe. Accordingly the reductiongear can be disposed in the dead space where the rigidity of the vehiclebody is high. As a result, it is possible to protect the reduction gear,and to enable a compact layout, which secures a large space foroccupants.

According to the seventh embodiment of the present invention, since thecenter pipe is provided in the center frame portion having the space foroccupants therein, the rigidity of the center frame portion can beimproved.

It should be noted that the present invention is not limited to theabove-described embodiment, and modification, improvement, and the likemay be made thereon as appropriate. For example, although the presentinvention has been described so far as being applied to an MUV (multiutility vehicle), the present invention is not limited to this but maybe applied to any type of vehicle having four or more wheels in the samemanner.

1. A frame structure for a vehicle comprising: a vehicle body framehaving a front-rear direction; a pair of occupant seats comprising adriver's seat and a passenger seat and arranged side by side in avehicle width direction substantially orthogonal to the front-reardirection; and a center pipe extending in the front-rear direction andarranged substantially on a center line of a vehicle body so as to passthrough positions between the driver's seat and the passenger seat inthe vehicle body frame.
 2. The frame structure for a vehicle accordingto claim 1, further comprising: a lower frame above which the centerpipe is arranged, the lower frame extending substantially in thefront-rear direction and disposed at both of left and right lowerportions of the vehicle body; a pair of left and right side framesextending in the front-rear direction and disposed substantially outsidethe lower frame in the vehicle width direction; and a pair of side pipeseach coupling two portions of each of the left and right side frames inthe front-rear direction.
 3. The frame structure for a vehicle accordingto claim 2, wherein the center pipe comprises, a joint point locatedsubstantially in front of the occupant seats; an upper center pipeextending frontward to the joint point from a portion of the vehiclebody frame located behind the occupant seats; a down center pipeextending upward and frontward to the joint point from a framesupporting the lower frame so as to pass through positions below andbetween the occupant seats; an upright center pipe extending rearwardand upward to the joint point from a portion of the lower frame locatedin front of the occupant seats; and a front center pipe extendingrearward and downward to the joint point from a portion of the vehiclebody frame located in front of the occupant seats, and wherein the uppercenter pipe, the down center pipe, the upright center pipe, and thefront center pipe are joined together at the joint point.
 4. The framestructure for a vehicle according to claim 3, further comprising: afront upper cross-member extending in front of the occupant seats tocouple the left and right side frames; and a pair of left and rightfront upper frames extending upward from front ends of the lower frameand then extending rearward to be connected to the front uppercross-member respectively at a first position and a second positionthereof, the left and right front upper frames so covering a frontportion of the vehicle body, wherein the front center pipe comprises twobranches extending frontward from the joint point and branched in thevehicle width direction so as to be connected to the front uppercross-member respectively at or in vicinities of the first position andthe second position of the front upper cross-member.
 5. The framestructure for a vehicle according to claim 1, further comprising: apropeller shaft disposed substantially along the center pipe andconfigured to transmit a driving force from an internal combustionengine to a front-wheel drive system.
 6. The frame structure for avehicle according to claim 3, further comprising: a propeller shaftdisposed along the center pipe and configured to transmit a drivingforce from an internal combustion engine to a front-wheel drive system;a foot control operable by an occupant's foot; and a reduction gearconnected to an intermediate portion of the propeller shaft andconfigured to convert a rotational direction of the propeller shaft intoa reverse direction, the reduction gear being located in front of theoccupant seats and behind the foot control and being disposed betweenthe down center pipe and the upright center pipe.
 7. The frame structurefor a vehicle according to claim 1, wherein the vehicle body framecomprises, a front frame portion supporting a front-wheel drive system;a center frame portion comprising the center pipe and providing a spacefor the occupant seats; and a rear frame portion supporting a rear-wheeldrive system.
 8. The frame structure for a vehicle according to claim 2,further comprising: a propeller shaft disposed substantially along thecenter pipe and configured to transmit a driving force from an internalcombustion engine to a front-wheel drive system.
 9. The frame structurefor a vehicle according to claim 3, further comprising: a propellershaft disposed substantially along the upper center pipe, the downcenter pipe, and the upright center pipe, and configured to transmit adriving force from an internal combustion engine to a front-wheel drivesystem.
 10. The frame structure for a vehicle according to claim 4,further comprising: a propeller shaft disposed substantially along theupper center pipe, the down center pipe, and the upright center pipe,and configured to transmit a driving force from an internal combustionengine to a front-wheel drive system.
 11. The frame structure for avehicle according to claim 4, further comprising: a propeller shaftdisposed along the center pipe and configured to transmit a drivingforce from an internal combustion engine to a front-wheel drive system;a foot control operable by an occupant's foot; and a reduction gearconnected to an intermediate portion of the propeller shaft andconfigured to convert a rotational direction of the propeller shaft intoa reverse direction, the reduction gear being located in front of theoccupant seats and behind the foot control and being disposed betweenthe down center pipe and the upright center pipe.
 12. The framestructure for a vehicle according to claim 5, further comprising: a footcontrol operable by an occupant's foot; and a reduction gear connectedto an intermediate portion of the propeller shaft and configured toconvert a rotational direction of the propeller shaft into a reversedirection, the reduction gear being located in front of the occupantseats and behind the foot control and being disposed between the downcenter pipe and the upright center pipe.
 13. The frame structure for avehicle according to claim 2, wherein the vehicle body frame comprises,a front frame portion supporting a front-wheel drive system; a centerframe portion comprising the center pipe, the left and right sideframes, and the side pipes, and providing a space for the occupantseats; and a rear frame portion supporting a rear-wheel drive system,and wherein the lower frame supports the front frame portion, the centerframe portion, and the rear frame portion.
 14. The frame structure for avehicle according to claim 3, wherein the vehicle body frame comprises,a front frame portion supporting a front-wheel drive system; a centerframe portion comprising the joint point, the upper center pipe, thedown center pipe, the upright center pipe, and the front center pipe,and providing a space for the occupant seats; and a rear frame portionsupporting a rear-wheel drive system, and wherein the lower framesupports the front frame portion, the center frame portion, and the rearframe portion.
 15. The frame structure for a vehicle according to claim4, wherein the vehicle body frame comprises, a front frame portioncomprising the left and right front upper frames and supporting afront-wheel drive system; a center frame portion comprising the jointpoint, the upper center pipe, the down center pipe, the upright centerpipe, the front center pipe, and the front upper cross-member, andproviding a space for the occupant seats; and a rear frame portionsupporting a rear-wheel drive system, and wherein the lower framesupports the front frame portion, the center frame portion, and the rearframe portion.
 16. The frame structure for a vehicle according to claim5, wherein the vehicle body frame comprises, a front frame portionsupporting the front-wheel drive system; a center frame portioncomprising the center pipe and providing a space for the occupant seats;and a rear frame portion supporting the rear-wheel drive system, andwherein the lower frame supports the front frame portion, the centerframe portion, and the rear frame portion.
 17. The frame structure for avehicle according to claim 6, wherein the vehicle body frame comprises,a front frame portion supporting the front-wheel drive system; a centerframe portion comprising the center pipe, the foot control, and thereduction gear, and providing a space for the occupant seats; and a rearframe portion supporting the rear-wheel drive system, and wherein thelower frame supports the front frame portion, the center frame portion,and the rear frame portion.
 18. A vehicle comprising: an internalcombustion engine; a vehicle body frame having a front-rear directionand supporting the internal combustion engine; a pair of occupant seatscomprising a driver's seat and a passenger seat and arranged side byside in a vehicle width direction substantially orthogonal to thefront-rear direction; and a center pipe extending in the front-reardirection and arranged substantially on a center line of a vehicle bodyso as to pass through positions between the driver's seat and thepassenger seat in the vehicle body frame.